Micro-mechanical devices or micro-electromechanical systems (MEMS) are micron-scale devices, often with moving parts, that may be fabricated using traditional semiconductor processes such as optical lithography, metal sputtering, oxide deposition, and plasma etching, which have been developed for the fabrication of integrated circuits.
Micromirrors, such as the DLP™ micromirror array from Texas Instruments, are a type of micro-mechanical device. Other types of micro-mechanical devices include accelerometers, pressure and flow sensors, gears, and motors. Pivoting or oscillating torsional hinged mirrors provide very effective and inexpensive replacements for spinning polygon shaped mirrors in printers and some types of displays. Further, other torsional hinged mirrors act as position indicators or pointer mirrors. Many of these MEMS devices have found wide commercial success.
Torsional hinged mirrors may be mirrors etched from a silicon substrate using processes similar to those used in the manufacture of semiconductor devices. The mirror and hinge structure may be processed out of a substrate comprised of a single silicon crystal, for example. However, manufacturing MEMS mirrors and hinge structures from one substrate may limit the mirror to the same thickness as the hinge. A thicker mirror may dictate a lower resonant frequency mirror. Therefore, mirror control may not be optimized for an application. New structures and methods for forming torsional hinge mirrors are thus needed to solve the above discussed problems.